As is stated in U.S. Pat. No. 3,530,634 (G. F. Adams), concrete is strong in compression but weak in tension and because it is likely to crack due to shrinkage and expansion and contraction from ambient temperature changes, it is advisable to embed steel reinforcing rods or bars or mesh in the concrete as the concrete is being cast. The resulting concrete and reinforcing structure is commonly known as reinforced concrete.
U.S. Pat. No. 3,530,634 furthermore indicates that there are various types of support brackets which find utility in supporting the reinforcing rods while the concrete is being poured so that the rods will be properly positioned within the concrete when it sets. A number of patents disclose such supports, such as, for example, U.S. Pat. Nos. 1,268,887; 1,841,699; 1,880,710; 3,788,025; and 4,085,559. In addition, for purposes of background information, reference may be made to German Pat. No. 2,228,969 and to British Pat. No. 904,766.
U.S. Pat. No. 1,268,887 shows a reinforcing device comprising a skeleton member having a plurality of ends which are thin, substantially flat and somewhat flexible. These ends are fashioned with cut-off portions having constricted communication to an edge of the skeleton member whereby the flexing of the material bordering the constricted cut-out area enables the insertion of an object fitted to the remainder of the cut-out area. This construction enables the installation of reinforcing devices or tie braces in concrete forms to be ultimately embedded in concrete constructions.
U.S. Pat. No. 1,841,699 reveals a bar support and spacer constructed of a single piece of wire which is fabricated to form a bar supporting part and a spacing part. The wire is bent to provide a pair of downwardly diverging legs with a horizontal foot which is exposed in the ultimately cast concrete.
D. H. Bitney in U.S. Pat. No. 1,880,710 reveals a reinforce support unit comprising a looped element having an arm which is straight and an arm which is angled and provides a base member. A cross piece is disposed transversely of the aforesaid arm and is provided with an upwardly facing loop adapted to receive a reinforce bar and support the same for being embedded in concrete which is cast thereabout.
S. Holmes in U.S. Pat. No. 3,788,025 discloses a chair support for reinforcing rods of the type supporting in right angular relationship two reinforcing rods used in the construction of concrete slabs. The chair has a lower arched base part and an upper rod supporting part integral with the base. The base is an arched structure with means providing lateral, longitudinal and vertical support and strength. The rod supporting part comprises two spaced arms the lower parts of which form a saddle for receiving one reinforcing rod and the upper part of each of which is formed by two spaced upstanding inwardly concave arms the upper ends of which are spaced to provide an opening through which a second reinforcing rod may be introduced.
U.S. Pat. No. 4,085,559 (R. Ilukowicz) discloses a hog slat reinforcing bar support which comprises a one-piece plastic body with spaced support portions for respective reinforcing bars. Each portion includes a surrounding wall with an opening through which the associated reinforcing bar can be inserted and held within the support portion. The portions may be connected by a connection piece with projecting members extending laterally from the body and defining a plurality of support points by which the body can be stabily supported in a hog slat form. The portions may also be supported on a structure in the shape of an A-frame.
British Pat. No. 904,766 reveals an X-shaped device at the extremities of which are provided receptacles for partially encircling reinforcing rods. The lowermost of the receptacles are provided with pins which present a substantially reduced contact with the floor of the form in which the concrete is to be cast.